The invention relates to a control arrangement for a system of circulating shelving which, in conjunction with at least one other system of circulating shelving provided with an identical control arrangement, is controllable by a data processing system and is provided with storage places for stored goods in the form of a multiplicity of carriers moveable by a drive system, the control arrangement being allocated a first device for detecting the position of the carriers, a second device for detecting the occupancy of the storage places and a data station provided with a data terminal and a data transmission device, the data station being connectable via a receive line, a transmit line and a return line to the data station of the control arrangement of the other system of circulating shelving and to a data station of the data processing system, with the receive line connected to a signal input of the data terminal, the transmit line to a signal output of the data transmission device and the return line to the system earth of the data station.
Control arrangements of this type are primarily used in large facilities having several systems of circulating shelving such as are described, for example, in the journal "Distribution", Volume 1-2/1983, pages 16 and 17.
In small systems of circulating shelving, a relatively simple collating system (file cards) is sufficient to know the place to which a certain item of stored goods is allocated. The drive system can then be manually set in motion until the desired carrier is in front of the service table. In large facilities, however, the support of a data processing system cannot be dispensed with. Each part to be stored is provided with an identification number and by entering this identification number into an input unit, information is obtained from the data processing system on where the relevant part is located or to where it must be brought. Each system of circulating shelving must therefore be allocated a control arrangement which contains a data station which then analyses and displays the information supplied by the data processing system and causes the drive system to move the identified carrier in front of a service table. In some systems, the issuing or receiving of stored goods can even be performed automatically. At the least, however, the data station contains a display unit which shows at which position the desired item of stored goods can be found. This can be, for example, coordinate data or a display strip reaching along the entire length of the service table.
Certain terms are defined in standards. Thus, for example, DIN 44 302 states that a data station consists of a data terminal and a data transmission device. The data terminal essentially comprises input, output, arithmetic and control units and memories. Inside the data terminal, the digital data are transferred in such a manner that binary elements, from which a character is composed, are in each case simultaneously transferred via a corresponding number of interface lines. In 8-bit technology, for example, parallel transfer accordingly takes place via eight interface lines. The data transmission device essentially has the task of establishing a connection with another data station which requires much less expenditure in lines. For this purpose, the digital data are transmitted in such a manner that the binary elements of which a character is composed are successively transferred via an interface line. This refers in each case to one direction of transmission. For an interactive connection, therefore, a transmit line and a receive line and a common return line are needed.
A data processing system is connected to a control arrangement of the type described in such a manner that three lines are run between the data station of the control arrangement and the corresponding data station of the data processing system. However, if several control arrangements are to be connected to one data processing system, a multiplexer has to be interposed. Such an additional device causes a considerable increase in cost, of an order of magnitude of about DM 30,000.00. To this is added greater installation and mounting expenditure and an increase in susceptibility to interference.